390 



GEOLOGY OF THE SECOND DISTRICT. 



lOU. 



1. Bumastus trentonensis. 



2. Ciilymene senaria. 



3. IllEEnus trentonensis. 



4. Sphceroraa bumastiformis (Eights). 



5. Calymene. 



6. Ceraums pleurexanthemus. 



7. Trinuclcus tesseilatus. 



No. 1 has not been found in place ; the fine specimen from which the drawing was made, 

 was found by a laborer in Hogansburgh, in a boulder of black bituminous limestone. The 

 boulder is identical with the black limestone of Montreal, which contains the Trenton fossils. 

 Upon the fragment containing the specimen, is discoverable a portion of a strophomena, 

 known also to belong to this rock ; there can be no doubt, therefore, of the position which it 

 occupies. But usually where a fossil has been obtained from a boulder, no account has 

 been taken of it. No. 1 is allied both to Bumastus and Isotelus, or seems to be an interme- 

 diate genus : it is probably a rare fossil. 



No. 2. The Calymene senaria is one of the most abundant fossils in this rock. In the 

 Second district, it is found at Glen's-Falls, Esse.x and Plattsburgh ; and it is also found at 

 Cumberland Head, or the opposite shore in Vermont, where the slaty limestone of the trenton 

 rock is found. In some places, as at Essex, it seems to have congregated in immense num- 

 bers : nearly a hundred heads, in an imperfect state, were observed upon one orthoceratite. 

 This species has generally been mistaken for the Calymene blumenbachii, which belongs to 

 rocks higher in the series. 



No. 3. For this small trilobite, I am indebted to my friend. Dr. Crawe, of Watertown. 

 It seems to be rather rare, though it has been found in the valley of the Mohawk. The spe- 

 cimen from which the drawing was taken, was found at Watertown. 



